Battle of Mons Aries

The Battle of Mons Aries was fought between the Roman Republic and an invading Volsci army to the south of Rome in 396 BC. Two Volscian armies under their king Marcus Crispus and their general Decimus Marcellus marched on Rome from Antium in the south, and they found the city's approaches guarded by the Roman general Marcus Furius Camillus' Legio I Alaudae. The Romans engaged the larger Volscian army in battle and destroyed it, and Camillus was recognized as the savior of Rome.

Background
In 399 BC, the Roman Republic went to war with the Etruscan city-state of Veii in the north, and their Italic rivals, the Volsci, prepared to strike at Rome from the south as Rome was distracted. However, Rome was able to conquer Veii in 397 BC, and, by that time, the Volsci had prepared several large armies for a campaign against the Romans and their Hernici allies. The Volsci succeeded in capturing Anagni and forcing the Hernici king Publius Glabrio to become a client ruler, and the emboldened Volsci proceeded to declare war on the Roman Republic. The armies of the Volsci king Marcus Crispus and his general Decimus Marcellus - totalling almost 3,500 troops, marched north from Antium and into southern Rome, preparing to lay siege to Rome. However, the great Roman general Marcus Furius Camillus, the conqueror of Veii, brought his hardened Legio I Alaudae south from Veii, leaving the defense of the city in the hands of the new Legio III Etrusca. Legio I Alaudae marched into the city of Rome before encamping to the south of the city gates, hoping to battle the Volsci outside of the city walls to prevent any harm from coming to the city in the coming battle. His legion, combined with the strength of the garrison under Decimus Plotius Lactuca, numbered just over 2,800 troops, almost 1,000 fewer troops than the Volsci army.

Battle
The Volsci king decided to destroy Legio I Alaudae before advancing into Rome and humbling his people's arch-nemesis. The Volsci attacked the Romans outside of the city walls, and the two Volsci armies joined forces in order to assault the legion. The Roman legion formed a defensive line, and its garrison reinforcements joined their formation, creating a wide "V"-shape; the Volscians would advance towards the center of the V, and the two wings would close in on the attackers. Sure enough, the warlike Volsci focused on charging the Roman center, allowing for the Roman flanks to close in on the Volsci from the sides. The Volsci skirmishers were easily routed, as they were not prepared for melee combat, and the Romans charged the Volsci spearmen from behind as the Roman center held firm against enemy attacks, with encouragement from their legate. The Roman wings swung around to cut off the Volsci escape, and Romans closed in from all sides to slaughter the large pocket of panicking Volscian warriors. Occasionally, the Volsci decided to turn and fight, but Camillus himself charged at their skirmishers with his cavalry bodyguards, slaughtering the hapless slingers. Decimus Marcellus himself was slain after his bodyguard unit was cornered and engaged by multiple Roman cohorts, and his king Marcus Crispus fled, with the Romans never managing to locate his fleeing bodyguards.

Aftermath
The Romans won a decisive victory at Mons Aries, reducing the Volscian army to just over 1,000 men, a third of their original army. The Volscians withdrew into their home province of Antium, and Camillus, seeking to slay their king Marcus Crispus and decisively defeat them, invaded Antium and inflicted a much closer defeat on the Volsci in the Battle of Aricia.